Title: Influence of deformation induced nanoscale twinning and FCC-HCP transformation on hardening and texture development in medium-entropy CrCoNi alloy

Abstract

Texture evolution during room-temperature tensile testing of recrystallized equimolar CrCoNi was studied using electron backscatter diffraction and electron channeling contrast imaging on specimens from interrupted tests. Dominant deformation mechanisms included slip at low strains and deformation twinning at larger strains, which were accompanied by the development of a strong <111> texture parallel to the tensile axis. Highly deformed material also contained nanotwin/hcp lamellae, which have previously been hypothesized to act as potent barriers for non-coplanar dislocations. To examine this hypothesis, mean-field modeling was performed using the viscoplastic self-consistent framework with varying ratios for hardening by slip and twinning. In the optimal model, twinning produced approximately three times as much non-coplanar hardening as slip, which is larger than previous observations in other twinning-induced plasticity materials that do not form twin/hcp lamellae. Additional full-field elasto-viscoplastic simulations were performed using the fast Fourier transform (EVP-FFT) method to examine intragranular rotation and the effect of initial grain orientation on the deformation mode. Grains with initial orientations near <111> had the greatest propensity for deformation twinning while grains near <100> were more likely to deform by slip even at large strains. In conclusion, excellent quantitative agreement was obtained between the experiments and EVP-FFT model.

Authors:

Slone, C. E. ^[1]; Chakraborty, S. ^[2]; Miao, Jiashi ^[3]; George, Easo P.  ^[4];

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Mills, Michael J. ^[1]; Niezgoda, S. R. ^[2]

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+ Show Author Affiliations

1. The Ohio State Univ., Columbus, OH (United States). Center for Electron Microscopy and Analysis; The Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering
2. The Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering
3. The Ohio State Univ., Columbus, OH (United States). Center for Electron Microscopy and Analysis
4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division; Univ. of Tennessee, Knoxville, TN (United States). Materials Science and Engineering Dept.

Publication Date:

Mon Oct 01 00:00:00 EDT 2018

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1462861

Alternate Identifier(s):

OSTI ID: 1496404

Grant/Contract Number:  

AC05-00OR22725; -60050072; FE0027776

Resource Type:

Accepted Manuscript

Journal Name:

Acta Materialia

Additional Journal Information:

Journal Volume: 158; Journal Issue: C; Journal ID: ISSN 1359-6454

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Medium- and high-entropy alloys; Twinning; Work-hardening modelling; EBSD; Texture